Dotnet CLI considers any file ending in "proj" as a project

### Describe the bug
Dotnet CLI commands will fail if there are more than one files with their extension ending with "proj", even if not valid project files

### To Reproduce

1- Create a C# console project with a solution
2- Create a file with an extension ending with "proj" (in my case it was ".omniproj" but i could reproduce it with other file names ending in "proj")
3- Try to use any dotnet CLI command that acts on the current project. I used `dotnet add package MemoryPack`
4- Watch the ``Found more than one project in ``. Specify which one to use.`` happen.

### Exceptions (if any)

``Found more than one project in ``. Specify which one to use.``
### Further technical details
details of dotnet --info

.NET SDK:
Version: 9.0.302
Commit: bb2550b9af
Workload version: 9.0.300-manifests.7cc9053d
MSBuild version: 17.14.13+65391c53b

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19045
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\9.0.302\

.NET workloads installed:
[android]
Installation Source: SDK 9.0.300, VS 17.14.36301.6
Manifest Version: 35.0.61/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.android\35.0.61\WorkloadManifest.json
Install Type: Msi

[aspire]
Installation Source: SDK 9.0.300, VS 17.14.36301.6
Manifest Version: 8.2.2/8.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\8.0.100\microsoft.net.sdk.aspire\8.2.2\WorkloadManifest.json
Install Type: Msi

[ios]
Installation Source: SDK 9.0.300, VS 17.14.36301.6
Manifest Version: 18.4.9289/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.ios\18.4.9289\WorkloadManifest.json
Install Type: Msi

[maccatalyst]
Installation Source: SDK 9.0.300, VS 17.14.36301.6
Manifest Version: 18.4.9289/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.maccatalyst\18.4.9289\WorkloadManifest.json
Install Type: Msi

[maui]
Installation Source: SDK 9.0.300
Manifest Version: 9.0.51/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.maui\9.0.51\WorkloadManifest.json
Install Type: Msi

[maui-windows]
Installation Source: SDK 9.0.300, VS 17.14.36301.6
Manifest Version: 9.0.51/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.maui\9.0.51\WorkloadManifest.json
Install Type: Msi

[tvos]
Installation Source: SDK 9.0.300
Manifest Version: 18.4.9289/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.sdk.tvos\18.4.9289\WorkloadManifest.json
Install Type: Msi

[wasm-experimental]
Installation Source: SDK 9.0.300
Manifest Version: 9.0.5/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.workload.mono.toolchain.current\9.0.5\WorkloadManifest.json
Install Type: Msi

[wasm-tools]
Installation Source: SDK 9.0.300
Manifest Version: 9.0.5/9.0.100
Manifest Path: C:\Program Files\dotnet\sdk-manifests\9.0.100\microsoft.net.workload.mono.toolchain.current\9.0.5\WorkloadManifest.json
Install Type: Msi

Configured to use loose manifests when installing new manifests.

Host:
Version: 9.0.7
Architecture: x64
Commit: 3c298d9f00

.NET SDKs installed:
8.0.412 [C:\Program Files\dotnet\sdk]
9.0.108 [C:\Program Files\dotnet\sdk]
9.0.302 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.18 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.18 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
Not set

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

- Not IDE specific since i was trying this in PowerShell 7.4.11